Python 中的 UDP 客户端/服务器套接字

UDP Client/Server Socket in Python

提问by user3335367

I'm new to python and sockets and am trying to write an echoing client/server socket. I have written the server so that 30% of the packets are lost. I programmed my client to timeout after one second since the packet could be lost. However, whenever I run my client socket, my output is 100% REQUEST TIMED OUT. I'm assuming I'm getting this output because my server is never receiving the message. I've looked over my code multiple times and cannot figure out why I am constantly getting this output. Below is my code for my server and client sockets. Any help would be appreciated.

我是 python 和套接字的新手，正在尝试编写一个回显客户端/服务器套接字。我已经编写了服务器，以便丢失 30% 的数据包。由于数据包可能丢失，我将我的客户端编程为一秒后超时。但是，每当我运行我的客户端套接字时，我的输出都是 100% REQUEST TIMED OUT。我假设我得到这个输出是因为我的服务器从未收到消息。我已经多次查看我的代码，但无法弄清楚为什么我不断得到这个输出。下面是我的服务器和客户端套接字的代码。任何帮助，将不胜感激。

Server Socket:

服务器套接字：

 # We will need the following module to generate randomized lost packets
    import random
    from socket import *

    # Create a UDP socket
    # Notice the use of SOCK_DGRAM for UDP packets
    serverSocket = socket(AF_INET, SOCK_DGRAM)

    # Assign IP address and port number to socket
    serverSocket.bind(('', 12000))

    while True:
        # Generate random number in the range of 0 to 10
        rand = random.randint(0, 10)

        # Receive the client packet along with the address it is coming from
        message, address = serverSocket.recvfrom(1024)

        # Capitalize the message from the client
        message = message.upper()

        # If rand is less is than 4, we consider the packet lost and do notrespond
        if rand < 4:
            continue

        # Otherwise, the server responds
        serverSocket.sendto(message, address) 

Client Socket:

客户端套接字：

import time
from socket import *

pings = 1

#Send ping 10 times 
while pings < 11:  

    #Create a UDP socket
    clientSocket = socket(AF_INET, SOCK_DGRAM)

    #Set a timeout value of 1 second
    clientSocket.settimeout(1)

    #Ping to server
    message = 'test'

    addr = ("127.0.0.1", 12000)

    #Send ping
    start = time.time()
    clientSocket.sendto(message, addr)

    #If data is received back from server, print 
    try:
        data, server = clientSocket.recvfrom(1024)
        end = time.time()
        elapsed = end - start
        print data + " " + pings + " "+ elapsed        

    #If data is not received back from server, print it has timed out  
    except timeout:
        print 'REQUEST TIMED OUT'

    pings = pings - 1

采纳答案by bsa

I tested your code, and it works as expected on my machine. Your issue might not be your code. It could be a firewall or something else blocking all the packets on the loopback interface (127.0.0.1). Depending on your operating system, try testing with a packet monitor like Wireshark.

我测试了你的代码，它在我的机器上按预期工作。您的问题可能不是您的代码。它可能是防火墙或其他阻止环回接口 (127.0.0.1) 上所有数据包的东西。根据您的操作系统，尝试使用 Wireshark 之类的数据包监视器进行测试。

Also, here are a few suggestions on how to improve your code to be more Pythonic:

此外，这里有一些关于如何改进您的代码以使其更加 Pythonic 的建议：

Server

服务器

import random
import socket

server_socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
server_socket.bind(('', 12000))

while True:
    rand = random.randint(0, 10)
    message, address = server_socket.recvfrom(1024)
    message = message.upper()
    if rand >= 4:
        server_socket.sendto(message, address)

Client

客户

import time
import socket

for pings in range(10):
    client_socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    client_socket.settimeout(1.0)
    message = b'test'
    addr = ("127.0.0.1", 12000)

    start = time.time()
    client_socket.sendto(message, addr)
    try:
        data, server = client_socket.recvfrom(1024)
        end = time.time()
        elapsed = end - start
        print(f'{data} {pings} {elapsed}')
    except socket.timeout:
        print('REQUEST TIMED OUT')

回答by Fastidious

Here is an alternative with asyncio.

这是 asyncio 的替代方案。

import asyncio
import random

class EchoServerProtocol:
    def connection_made(self, transport):
        self.transport = transport

    def datagram_received(self, data, addr):
        message = data.decode()
        print('Received %r from %s' % (message, addr))
        rand = random.randint(0, 10)
        if rand >= 4:
            print('Send %r to %s' % (message, addr))
            self.transport.sendto(data, addr)
        else:
            print('Send %r to %s' % (message, addr))
            self.transport.sendto(data, addr)


loop = asyncio.get_event_loop()
print("Starting UDP server")

# One protocol instance will be created to serve all client requests
listen = loop.create_datagram_endpoint(
    EchoServerProtocol, local_addr=('127.0.0.1', 12000))
transport, protocol = loop.run_until_complete(listen)

try:
    loop.run_forever()
except KeyboardInterrupt:
    pass

transport.close()
loop.close()